1. Field of the Invention
The present invention relates to a data push service system and method for use in a mobile communication system. More particularly, the present invention relates to a data push service system and method using a heterogeneous network.
2. Description of the Related Art
Data push service has been widely used as a data service format provided to a user who gains access to the Internet. The data push service can provide the user with a variety of functions, such as a Short Message Service (SMS) of a mobile communication network, over an IP network. The data push service can be transferred from a server to the user without receiving a user's request, and can provide the user with not only text data, but also multimedia data such as video and audio data.
The data push service over a mobile communication network will hereinafter be described with reference to FIG. 1.
Referring to FIG. 1, if a Push Initiator (PI) 100 generates data to be transmitted to a user, it transmits a push request to a Push Proxy Gateway (PPG). In this case, provided that a Point-to-Point Protocol (PPP) session is positioned between an Access Terminal (AT) 130 and a Packet Data Service Node (PDSN) 120, and the PPG 110 recognizes an Internet Protocol (IP) address of the AT 130, the PPG 110 transmits push data to the AT 130 over the PDSN 120. However, if there is no PPP connection between the AT 130 and the PDSN 120, or the PPG 110 is unable to recognize the IP address of the AT 130, push data is unable to be transmitted over the IP network, such that the PPG 110 transmits a request signal to a Short Message Service Center (SMSC) 140 to convert the push data into an SMS message, and transmits the SMS message to the AT 130 over a Mobile Switching Center (MSC) 150.
However, provided that the aforementioned data push service method for use in the mobile communication system is unable to convert the push data into the SMS message, or requires an IP connection between the PI or PPG and the AP in the same manner as in a multimedia service, it is impossible for the data push service method to provide a user with a reliable data push service.
With the increasing development of communication technologies and the increasing demands of users, a variety of radio access technologies and terminals capable of providing the users with data services have recently been proposed. A representative example is a heterogeneous network environment indicative of a mobile communication environment in which a variety of access networks using different radio access technologies are combined with each other. If a specific AT can select and access an optimum access network according to a user's selection or service categories and wireless environment variation in the heterogeneous network environment, the specific AT is called a Hybrid Access Terminal (HAT).
Although the aforementioned data push service method is applied to the heterogeneous network environment, the AT can gain access to a variety of access networks in the heterogeneous network environment. Therefore, in order to allow the PPG to correctly manage an AT's connection state, the AT must acquire a connection state from all of the accessible access networks.